Field of the Invention
The present invention relates to an information sharing system for performing control to allow apparatuses to share information.
Description of the Related Art
There is conventionally known an information sharing system that causes a plurality of information processing apparatuses connected via a network to share common data.
Japanese Patent Laid-Open No. 2004-86800 describes a synchronization system that transmits, from a client to a server, data contents updated after previous data synchronization between the server and the client. Japanese Patent Laid-Open No. 2012-123573 describes a sharing system that causes a plurality of multifunction peripherals connected via a network to share user information.
In the system described in Japanese Patent Laid-Open No. 2004-86800, when the server and a plurality of clients share setting information, a setting change desired by the system administrator or the user of a client may not be reflected on the system.
For example, out of two clients that share information with a server, the first client communicates with the server. While the second client temporarily stops communication with the server, the first client that is communicating with the server adds user information of the local apparatus. The second client that has stopped the communication with the server also adds user information of the local apparatus.
In this case, in the system described in Japanese Patent Laid-Open No. 2004-86800, the first client notifies the server of the addition of the user information. The server adds the user information to be held in it in accordance with the notification from the first client. On the other hand, the second client cannot notify the server of the addition of the user information because of the stop of the communication with the server.
If the number of pieces of user information held in the server reaches the upper limit upon adding the user information according to the notification from the first client, the user information addition notification that is transmitted from the second client after resumption of the communication with the server is not reflected on the server.
The above-described problem occurs not only in the above example but also in a case in which the first and second clients communicate with the server and add user information at the same timing. That is, only addition of user information notified first is reflected on the server. Addition of the other piece of user information is not reflected on the server because the number of pieces of user information held in the server exceeds the upper limit.
The problem of the same contents described above concerning the system of Japanese Patent Laid-Open No. 2004-86800 arises even in a case in which one of the plurality of multifunction peripherals included in the information sharing system of Japanese Patent Laid-Open No. 2012-123573 is used as a server, and the remaining multifunction peripherals are used as clients. That is, even if the system administrator or the user of a client wants to reflect, on the server, addition of user information by the second client with priority over addition of user information by the first client, only the data change by the first client is reflected on the server.
In the above-described examples, the number of users of user information has an upper limit. However, the above-described problem may occur not only for the user information but also for any data other than user information used by the clients. The same problem as described above may arise even in a case in which not the number of data but the data capacity has an upper limit.